1. Field of the Invention
The present invention relates to an electron beam apparatus including a first substrate having an region from which electrons are emitted, a second substrate having an region which is irradiated by the emitted electrons, and a spacer arranged between the first and the second substrates for forming an atmospheric pressure resistant structure, and to an image display apparatus using the electron beam apparatus.
2. Related Background Art
Two kinds of electron-emitting devices which are a hot-cathode device and a cold-cathode device are conventionally known. As the cold-cathode device, for example, a surface conduction type electron-emitting device, a field emission type (FE type) electron-emitting device, a metal/insulating layer/metal type (MIM type) electron-emitting device and the like are known.
The surface conduction type electron-emitting device utilizes the phenomenon in which electrons are emitted by the current flowing parallel to the surface of the thin film which is formed on the substrate and has a small area. As the surface conduction type electron-emitting device, for example, the following devices are known: the device using a SnO2 thin film which is disclosed in M. I. Elinson, xe2x80x9cRadio Eng. Electron Physxe2x80x9d, 10, 1290, (1965), the device using an Au thin film which is disclosed in G. Dittmer, xe2x80x9cThin Solid Filmsxe2x80x9d, 9, 317 (1972), the device using In2O3/SnO2 thin film which is disclosed in M. Hartwell and C. G. Fonstad, xe2x80x9cIEEE Trans. ED Conf.xe2x80x9d, 519 (1975), the device using a carbon thin film which is disclosed in H. Araki, xe2x80x9cVacuumxe2x80x9d, vol. 26, No. 1, 22 (1983), and the like.
Because especially the surface conduction type electron-emitting device has a simple structure and is easily produced among the cold-cathode type electron-emitting devices, the surface conduction type electron-emitting device has an advantage that many devices can be formed over a large area. Moreover, as the application of the surface conduction type electron-emitting device, for example, the application to an image display apparatus, an image formation apparatus such as an image recording apparatus and the like, a charged beam source, and the like has been researched. In particular, as the application to the image display apparatus, for example, the present applicant proposed an image display apparatus using surface conduction type electron-emitting devices in combination with phosphors which emitted light by being irradiated by electron beams as it was disclosed in U.S. Patent No. 5,066,883. The image display apparatus using the surface conduction type electron-emitting devices in combination with the phosphors is expected to have superior characteristics in comparison with other conventional type image display apparatus. For example, even if the image display apparatus is compared with a liquid crystal display apparatus which has come into wide use recently, the image display apparatus has advantage in that the image display apparatus does not need any backlight because the apparatus is self light emission type, and in that the image display apparatus has a wide view angle.
On the other hand, a method for driving many arranged FE type electron-emitting device is disclosed in U.S. Pat. No. 4,904,895 by the present applicant. Moreover, as an example of the application of the FE type electron-emitting device to an image display apparatus, for example, a flat-panel type display apparatus reported by R. Meyer (R. Meyer xe2x80x9cRecent Development Micro-tips Display at LETIxe2x80x9d, Tech. Digest of 4th Int. Vacuum Micro Electronics Conf. Nagahama, pp. 6-9 (1991)) is known.
Moreover, in recent years, it has been examined to use a carbon nanotube as an electron-emitting device.
Among the image formation apparatus using the electron-emitting devices as described above, because the flat panel type display apparatus having a thin depth can save a space and is light in weight, the flat panel type display is attracting public attention as one to replace a cathode-ray tube type display apparatus.
FIG. 11 is a perspective view showing an example of the flat panel type image display apparatus. The panel of the display apparatus is shown in a partially cutaway state for showing the internal structure of the apparatus. As shown in FIG. 11, a plurality of cold-cathode devices (hereupon, surface conduction type electron-emitting devices are shown as an example) 3112, which are electron sources, is formed in a matrix on a substrate 3111. The substrate 3111 is piled on a rear plate 3115. The rear plate 3115, a side wall 3116 forming a frame, and a face plate 3117, on which a fluorescent film 3118 and an anode electrode (a metal back) 3119 are formed, constitute an envelope (a hermetic container) for keeping the inside of the display panel vacuum. Incidentally, the cold-cathode devices 3112 are connected to wiring 3113 and 3114 arranged in a matrix.
The inside of the hermetic container is kept to be vacuum at about 1.33xc3x9710xe2x88x924 Pa (10xe2x88x926 Torr). The larger the display area of the image display apparatus becomes, the more the means for preventing the deformation or the destruction of the rear plate 3115 and the faceplate 3117 caused by atmospheric pressure difference between the inside of the hermetic container and the outside thereof becomes necessary. The method for preventing the deformation or the destruction by thickening the rear plate 3115 and the face plate 3117 causes the distortion of images and parallax when the image display apparatus is looked at obliquely in addition to the increase of the weight of the image display apparatus. Accordingly, as shown in FIG. 11, spacers (called as ribs in some cases) 312, which are made of relatively thin glass plates and are structural supporting members for withstanding the atmospheric pressure, are provided. By the spacers 3120, the interval between the rear plate 3115 and the face pate 3117, more correctly the interval between the substrate 3111, on which a multi-beam electron source is formed, and the metal back 3119, is normally kept to be several millimeters or less, and the inside of the hermetic container is kept to be highly vacuum, as described above.
The necessary number of the spacers 3120 judged from the structural viewpoint is effectively arranged. When the spacers 3120 are formed to have a length shorter than the image display region (the region in which the metal back 3119 is formed and the orthogonal projection region of the metal back 3119 to the rear plate 3115), the number of the spacers 3120 and the setting man-hour of the spacers 3120 are obliged to increase. Accordingly, it is preferable to provide the spacers 3120 having a length equal to the image display region or longer.
The image display apparatus described above has the following problems.
Electron beams emitted from the electron-emitting devices of the substrate 3111 on the rear plate 3115 to the face plate 3117 impinge on the face plate 3117. After the impingement, a part of the electrons are reflected as secondary electrons, and are emitted to the substrate 3111 and the spacers 3120. When the substrate 3111 is charged excessively owing to the secondary electrons which impinged on the substrate 3111, the substrate 3111 generate discharges, which give bad influence to images. Moreover, when the spacers 3120 is charged excessively owing to the secondary electrons which impinge on spacers 3120, the charging gives influence to the orbits of the electron beams near to the spacers 3120 to change the irradiation positions on the face plate 3117. Consequently, the uniformity of the images near to the spacers 3120 decreases to give bad influence to the image qualities.
It is known that the location of a potential regulation plate made of metal between the rear plate 3115 and the face plate 3117 in the state of being parallel to both the plates (the substrate) is effective. The potential regulation plate has thorough holes at the positions where electron beams pass through and at the positions where the spacers 3120 are arranged. However, it is very difficult to locate the potential regulation plate to keep the even intervals between the rear plate 3115 and the face plate 3117 all over the surfaces, and the spaces 3120 and the potential regulation plate are required to be fixed at accurate positions. Consequently, the cost was high.
In view of the problems as mentioned above, it is one objective of the present invention to provide an electron beam apparatus capable of locating an potential regulation plate and spacers simply and inexpensively between a rear plate being a first plate and a face plate being a second plate, and capable of decreasing the quantity of the charging of the electrons reflected by the second substrate on the first substrate and the spacers to make it possible to keep stable images. Another object of the present invention is provide an image display apparatus using the electron beam apparatus and a manufacturing method of the electron beam apparatus.
To achieve the objectives as mentioned above, the present invention provides an electron beam apparatus including a first substrate having a region from which electrons are emitted, a second substrate having a region which is irradiated with the emitted electrons, and at least one spacer located between the first substrate and the second substrate for forming an atmospheric pressure resistant structure. And, this apparatus is particularly unique in having at least one potential regulation plate including an aperture portion, through which electrons emitted from the first substrate pass, between the first substrate and the second substrate, wherein the potential regulation plate includes a recessed portion, to which the spacer fitted, on one principal surface of the potential regulation plate, and a part of the other principal surface of the potential regulation plate abuts on the first substrate or the second substrate in a state in which the spacer is fitted to the recessed portion.
Moreover, an image display apparatus of the present invention is an image display apparatus, comprising an electron beam apparatus of the present invention, wherein an image formation member forming an image by impingement of electrons is provided in the region of the electron beam apparatus, the region irradiated by emitted electrons.
According to the present invention, when the potential regulation plate is located between the first substrate and the second substrate and the fist substrate and the second substrate is joined to each other with a spacer interposed between them, the spacer is inserted in the recessed portion (a groove in the shape of a letter U, a letter U with a flat bottom, a letter V, or the like) formed on one principal surface of the potential regulation plate to arrange the spacer on the potential regulation plate. Because the intervals between the spacers are determined to be the intervals of the recessed portions of the potential regulation plate uniquely, the arrangement of the electron beam passing through apertures (aperture portions) and the spacers are accurate, and there in no need for using any expensive location apparatus.
As a result, the potential regulation plate and the spacers can be arranged between the first substrate and the second substrate simply and inexpensively. The quantity of electrons which have been reflected by the second substrate and are charged on the first substrate and the spacers can be decreased. Consequently, an electron beam apparatus which can keep stable images and an image display apparatus using the electron beam apparatus can be provided.
Moreover, a projected portion is formed on a portion of the other principal surface of the potential regulation plate, at which portion the potential regulation plate abuts on the first substrate or the second substrate. Thereby, the portion of the potential regulation plate where the through hole formed for making electron beams pass through the through hole is regulated by the height of the projected portion of the potential regulation plate. Consequently, the interval between the potential regulation plate and the first substrate or the second substrate can be kept to be uniquely constant all over the surface of the potential regulation plate.